The E18 error is fairly common. Here's some things that you can do to try to correct it. Have already fixed several cameras with this problem by using these methods:
http://www.e18error.com/repair.html

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Look at your memory card. SD cards have a slide switch along one edge. The position farthest from the metal contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

This is most likely a defective zoom rocker switch assembly. This will require major disassembly to repair and can usually be done fairly inexpensively. However, it's not a user serviceable problem and will need to be repaired by a qualified service technician.

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Hi,The black screen problem means the lens sensor is spoiled due to over exposure to heat. Its better to give it to cannon service centre. If your camera is under warranty period its well and good they will replace the lens sensor for free of cost.Thank you

Your zoom motor is probably stuck. Remove the two screws on the front side of the tiltable head. Pry off the two tilt caps using a small flat head screwdriver (they are glued on). Remove the 4 screws found under each cap. Now you can separate the two sides of the head and take out the two lenses (remember exactly how the lenses were positioned). Try pushing the flash in or out (it should move with a little force). See if the flash now responds before reassembling.